186 RIO PLATA. Dec. 1833. 



fine and calm, and the one previous to it equally so, ^vith 

 light and variable airs. Hence we cannot suppose that the 

 insects were blown off the land, but we must conclude that 

 they voluntarily took flight. The great bands of the Colias 

 seem at first to afford an instance hke those on record of 

 the migrations of Vanessa cardui;* but the presence of other 

 insects makes the case distinct, and not so easily intelligible. 

 Before sunset, a strong breeze sprung up from the north, 

 and this must have been the cause of tens of thousands 

 of the butterflies and other insects having perished. 



On another occasion, when seventeen miles off Cape 

 Corrientes, I had a net overboard to catch pelagic animals. 

 Upon drawing it up, to my surprise I found a considerable 

 number of beetles in it, and although in the open sea, they 

 did not appear much injured by the salt water. I lost some 

 of the specimens, but those which I presei^ved, belonged to 

 the genera, colymbetes, hydroporus, hydrobius (two species), 

 notaphus, cynucus, adimonia, and scarabcEus. At first, I 

 thought that these insects had been blown from the shore ; 

 but upon reflecting that out of the eight species, four were 

 aquatic, and two others partly so in their habits, it appeared 

 to me most probable that they were floated into the sea, 

 by a small stream which drains a lake near Cape Corrientes. 

 On any supposition, it is an interesting circumstance to find 

 insects, quite aUve, swimming in the open ocean, seventeen 

 miles from the nearest point of land. There are several 

 accounts of insects having been blown off the Patagonian 

 shore. Captain Cook observed it, as did more lately Captain 

 King in the Adventure. The cause probably is due to the want 

 of shelter, both of trees and hills, so that an insect on the 

 wing with an off-shore breeze, would be very apt to be blown 

 out to sea. The most remarkable instance I ever knew of 

 an insect being caught far from the land, was that of a large 

 grasshopper {Acrydium), which flew on board, when the 



* Lyell's Geology, vol. iii., p. 63. 



